﻿<p> </p>
<blockquote class="extDef">NOTE&nbsp; Definition according to ISO/CD 10303-42:1992<br>
A vertex_loop is a loop of zero genus consisting of a single vertex. A vertex can exist independently of a
vertex loop. The topological data shall satisfy the following constraint:  
<blockquote><img src="../../../figures/ifcvertexloop-math1.gif" width="132" height="18" border="0"></blockquote> 
</blockquote>

<blockquote class="note">NOTE&nbsp; Entity adapted from <strong>vertex_loop</strong> defined in ISO 10303-42.</blockquote>
<blockquote class="history">HISTORY&nbsp; New entity in IFC2x2.</blockquote>
<p class="spec-head">Informal Propositions:</p> 
<ol> 
 <li>A vertex loop has zero extent and dimensionality.</li> 
 <li>The vertex loop has genus 0.</li> 
</ol> 